Topic 1: Axion dark matter in the sky Topic 2: Learning Dark Energy properties from cosmological surveys

Abstract 1: The axion, motivated as a solution to the strong CP problem, is also a viable dark matter candidate. If the initial axion field is not homogenized by inflation, it can naturally imprint large isocurvature fluctuations at extremely small scales and form substructures with subplanetary masses. There have been proposals that appear capable of detecting substructures with such masses, which open the window to detect axion indirectly. In this talk, I will discuss the evolution of axion minihalos based on N-body simulations. The present-day abundance and density profiles of axion minihalos in the Universe are obtained by extrapolating the simulation results analytically, suggesting that axion minihalos are detectable in future observations.

Abstract 2: I will discuss optimal strategies to study Dark Energy properties with data from present and upcoming cosmological surveys. Then I will show a worked example obtained with present data including Planck measurements of the CMB and galaxy clustering data from the Dark Energy Survey. I will then comment on the relevance of these results at explaining existing tensions within the standard cosmological model.